Electrical-circuit breaker.



No. 820,421. PATBNTED MAY 15-, 1906.

- 0;. 1?. HUTGHINGS.

ELECTRICAL CIRCUIT BREAKER. rrmornox nun 00T.14.19 3.

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Specification of Letters Patent.

Patented May 15, 1906.

Application filed October 14, 1908. Serial No. 177,073-

To aZZ whont it may concern:

Be it known that 1, CHARLES F. Huron- INGS, a citizen of the United States, residing at Bay City, in the county of Bay and State of Michigan, have invented certain new and useful Improvements in Electrical-Circuit Breakers; and I- do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention is a circuit-breaker for use on electrical circuits, its object being to open the circuit if through defective wiring or from other causes the circuit becomes grounded or deflected from its proper path-as, for instance, by a leak of current or a short circuit through the frame or through the wiring of an electric machine.

The improvements consist in certain arrangements of parts in a circuit-breaker, whereby the cut-off switch is automatically opened, breaking the circuit when the strength of one of the two magnetic fields which control the switch-locking mechanism is changed relatively to the other or when the magnetic field of the controlling apparatus is shifted, due to a short circuit on the line or in the motor, as will be more fully set forth in the specification.

The particular mechanical arrangements and proportions of the parts of circuit-breaking apparatus are well known, and these de tails of construction can be varied to suit various working requirements but the essential features of this device consist in the arrangement of the solenoids that operate to release the switch when the current deviates from its proper course. The .circuits are illustrated in the accompanying drawings, in which' Figure 1 is a diagrammatic view showing the switch and the solenoids that control it. Fig. 2 is a sectional detail of the core and its supportingrod.

The arrangement and operation of the device are as follows:

M and M are motors or other electrical machines to be protected by the circuitb-reaking switch 1. The current enters the switch throu h the line L and passes through the switch-bl ade 1, the line 2, solenoid 3, the line 4, the motors M and M line 5, solenoid 6, and thence through the line L to its source or the ground.

It will be noticed that the two solenoids are connected in series with the machineto be protected, one solenoid being on each side, electrically considered, of the protected machine. In this case the full current required for the machines passes through both solenoids. When using very heavy currents, however, each solenoid may be shunt-connected to the line instead of being series-connected, thereby taking only a small part of the total current and permitting the use of small solenoid-wires.

The solenoids 3 and 6 are shown in the drawings as being arranged coaXially one above the other, so that their magnetic fields join in the center, causing them to operate as a single long solenoid. The lron core 7 is freely suspended within the solenoids 3 and 6, so that it is held magnetically under the influence of the two solenoids 3 and 6. The solenoids operate conjointly under the action of currents that are either e ual to the total line-current, as in the case il 1, or proportional thereto, as in the case where they are shuntconnected to the line, as above described. The core 7 has anaXial hole 7 through which a rod 8 passes freely. To support the core 7 from below, a washer 8 is secured to therod 8, and a short distance above the core 7 is a second washer 8 so placed that the core 7 can rise freely a short distance on the rod 8 before striking the washer 8 The upper end of the rod 8 is attached to a lever or latch 9 or its equivalent. This latch operates to hold the blade 1 in circuit against the resistance of the spring 10, that tends-to open it, as indicated by dotted lines in Fig. 1. The latch is insulated from the blade 1 either by engaging an insulatingblock 1 secured to the blade, or by any other suitable means.

It is apparent that the latch 9 will hold the blade 1 in its closed position so long as the core 7 remains stationary.

An examination of Fig. 1 shows that under normal conditions the same current must pass through both solenoids; but if, for illustration, there is an are or short circuit established from the motor M to the line L or to the ground the same current as before will pass through the solenoid 3 and line 4; but owing to the leakage produced by the short circuit a smaller current than before will pass through the line 5 and the solenoid 6. In extreme cases solenoid 6may become entirely inoperative. The effect is to partially or entirely shunt the solenoid 6, thus shifting in ustrated in Fig.

stantly the field of magnetic efiort to solenoid 3. Core 7 will be forcibly drawn up toward the solenoid 3. Its momentum increases as it moves up the rod 8, and it strikes the washer 8 a sharp blow that releases the latch 9 and the blade 1, which immediately opens under the action of the spring 10, thus cutting off all current from the motors M and 1W.

It will be noted that a device made after this system is not a limit-switchthat is, it does not break the circuit when the current strength reaches a predetermined maximum limit, but does break the circuit the instant a ground or dangerous short circuit occurs. The distinction between it and the so-called limit-switches is very apparent in practice. If a trolley-car motor is suddenly reversed in time of danger, the electrical load increases enormously, and a limit-switch immediately breaks the circuit when the intensity of current reaches the predetermined maximum or limit. Many serious accidents have resulted from this sudden loss of current and consequent inability to control the motor.

From the preceding description it has been seen that no increase of current, however great, can cause my improved device to break the circuit, but that the circuit will be instantly broken as soon as a leak or ground in the wiring occurs, thus preventing asudden rush of current and burning out of the motor.

While I have shown and described a single core 7 operating under the conjoint influence of two solenoids 3 and 6, one above the other, yet I do not desire to confine myself to this particular construction, as it is evident that it' might be accomplished in various ways. The essential "feature of this invention resides in the fact that the circuit is held normally closed,while the devices that actuate the circuit-breaker are under the normal conjoint influence of the two solenoids; but when that influence is made abnormal by the reduction of current through one of the solenoids the circuit-breaking device is made operative and the current is cut oil. I

What I claim as my invention, and desire to secure by Letters Patent, is as follows:

In a device of the class described, the combination with a source of current, the device to be protected, and circuit connections; of a circuit-breaker comprising a latch having a rod suspended therefrom a magnetizable core slidably mounted on said rod; a stop on said rod adapted to be actuated by said core in its upward movem ent; a solenoid surrounding the upper end of said core and having one end electrically connected to said circuitbreaker and having its other end connected to the electrical device to be protected; a second solenoid surrounding the other end of said core and connected to one end of said device, whereby current is carried through the circuit-breaker, first solenoid, device to be protected, second solenoid and thence back to the source of current.

In testimony whereof I a'l'l'iX my signature in presence of two witnesses.

CHARLES F. HUT CHIN GS. Witnesses:

J. S. SEE, W. I. CATncART. 

